Posted
by
samzenpus
on Wednesday June 25, 2014 @07:06PM
from the we're-going-to-need-a-bigger-setting dept.

ygslash (893445) writes Astronomers at the National Radio Astronomy Observatory announced that they have discovered what appears to be the coolest white dwarf ever detected. The white dwarf is formerly a star similar to our own sun which, after expending all of its fuel, has cooled to less than a chilly 3000 degrees Kelvin and contracted to a size approximately the same as Earth. A white dwarf is composed mostly of carbon and oxygen, and the astronomers believe that at that temperature it would be mostly crystallized, forming something like a huge diamond.

Considering that the high price of diamonds is a combination of the De Beers monopoly together with their massive PR campaigns to a) make people use diamonds as formal symbols of affection and b) to make people unwilling to sell them second-hand once they've been owned, they should be worried. On the other hand, this is 900 light years away, so maybe they'll just lobby against any research into FTL travel.

Is your relationship cold, shriveled and almost unimaginably distant? Astronomical diamonds may be for you!

Is your girlfriend upset that you didn't call the International Star registry and get a star named after her (written in book form in the library of congress) like all of her girlfriends did? Was she upset that you didn't care that much for her?

Well now is your chance to redeem yourself. Don't just name any old star after your girlfriend, get a star sized diamond named after her! If diamonds are a girls best friend, then after doing this you'll never have to "[sudo] make me a sandwich" again, as she'll b

Actually, if you want to apply SI correctly then 'K' is not an abbreviation, it's a unit symbol. Abbreviations are a language construct (and depend on the language), symbols are those things you use in mathematics.

Kaplan and his colleagues found this stellar gem using the National Radio Astronomy Observatoryâ(TM)s (NRAO) Green Bank Telescope (GBT) and Very Long Baseline Array (VLBA), as well as other observatories.

The National Science Foundation (NSF) Astronomy Portfolio Review committee chaired by Daniel Eisenstein of Harvard University recommended in August 2012 that the Robert C. Byrd Green Bank Telescope should be defunded over a five year period.[9] Further information on this divestiture can be found on the AUI webpage and at www.savethegbt.org.

In the fiscal year 2014 budget, the US Congress did not recommend divesting the Green Bank Telescope. The Telescope is looking for partners to help fund its $10 million annual operating costs.

How do they go from crystalized carbonmonoxide to a diamond? The diamond crystal lattice is exceptionally strong and only atoms of nitrogen, boron and hydrogen can be introduced into diamond during the growth at significant concentrations (up to atomic percents).If it's "mostly" oxygen and carbon it's not a diamond. That's simple chemistry.

If it's been gradually cooling for billions of years, I imagine that might create annealing-like conditions where the oxygen and carbon separate with the heavier solid oxygen at the core and a diamond lattice outside. So maybe it's diamond shell with a refreshing solid oxygen center?

This class of white dwarf stars are a mixture of primarily oxygen and carbon. Depending on the mass the amount of carbon and oxygen are roughly the same, but sometimes there is more oxygen. As the star cools it goes through a phase transition where the core becomes crystallized. This releases heat through two mechanisms: heat of crystallization and the release of gravothermal energy.

The inner crystallized section is enhanced in oxygen. The outer fluid mantel is enriched in carbon. Calling this a diamond is simply wrong. Perhaps at some point in the distant future one of these will cool and part of it will become a form of crystal carbon, but considering that the cooling time without mantle carbon crystallization is on the order of 10 Gigayears, it is not likely this has happened yet considering that the universe is around 13.6 gigayears old.

The Cooling of CO White Dwarfs: Influence of the Internal Chemical Distribution

White dwarfs are the remnants of stars of low and intermediate masses on the main sequence. Since they have exhausted all of their nuclear fuel, their evolution is just a gravothermal process. The release of energy only depends on the detailed internal structure and chemical composition and on the properties of the envelope equation of state and opacity; its consequences on the cooling curve (i.e., the luminosity vs. time relationship) depend on the luminosity at which this energy is released.

The internal chemical profile depends on the rate of the 12C(, )16O reaction as well as on the treatment of convection. High reaction rates produce white dwarfs with oxygen-rich cores surrounded by carbon-rich mantles. This reduces the available gravothermal energy and decreases the lifetime of white dwarfs.

In this paper we compute detailed evolutionary models providing chemical profiles for white dwarfs having progenitors in the mass range from 1.0 to 7 M, and we examine the influence of such profiles in the cooling process. The influence of the process of separation of carbon and oxygen during crystallization is decreased as a consequence of the initial stratification, but it is still important and cannot be neglected. As an example, the best fit to the luminosity functions of Liebert et al. and Oswalt et al. gives an age of the disk of 9.3 and 11.0 Gyr, respectively, when this effect is taken into account, and only 8.3 and 10.0 Gyr when it is neglected.

Calling this a diamond is simply wrong. Perhaps at some point in the distant future one of these will cool and part of it will become a form of crystal carbon, but considering that the cooling time without mantle carbon crystallization is on the order of 10 Gigayears, it is not likely this has happened yet considering that the universe is around 13.6 gigayears old...

OP here. Not claiming to know much about this; I just pointed out the NRAO announcement. But I assume that NRAO does have people that know something about the physics here.

They are not saying that the white dwarf is 3000 K - they would have detected it directly then. They are saying that it must be cooler than that, perhaps much cooler. Thus, they are speculating that this is an extremely old object, and that it may indeed have cooled enough to reach temperatures at which there would be carbon crystallizati

No, it's not. If we were talking about general chemistry, then it's like getting medical advice about the brain from a proctologist vs. somebody who took biology 101 in college. The proctologist still went to medical school and completed a residency which included a neurology rotation. However, in this case, these astronomers specialize in determining the composition of ginormous things, so it's pretty safe to assume that they're a bit more informed in that area than a typical physics major, and especial

It was one of a couple of TG-16 games they did on the Sega-CD. Funny thing was even though Lords of Thunder was basically the same game as the Duo-CD version the Sega-CD version of Dungeon Explorer was a totally new game.

But since its much smaller, the surface gravity would be much greater (you can go deeper into its gravitational well before you reach its surface). The sun has a surface acceleration of 275 m/s^2, or about 28 g. This white dwarf would have a surface acceleration of 3.33 Mm/s^2, or 3.3e5 g, more than ten thousand times higher. Attempt no landings there.

Yes, Amaurea right above your post laid that out pretty well, as do you.... but the OP didn't specify surface gravity. You would feel roughly the same effects (gravitationally) from it as you would from our sun at the same distance from center of mass; you'd simply be able to get much closer to center of mass on a white dwarf, baring being fried from the radiation output.